Nickel-chromium alloy and process of making same



Patented June 30, 1925.

v UNITED STATES PATENT OFFICE.

MILTON J. ROSENCRANTZ, OF NEW YORK, N. Y.

NICKEL-CHROMIUM ALLOY AND PROCESS OF MAKING- SAME.

No Drawing. Application filed June 13, 1919, Serial No. 304,018. Renewed August 21, 1924.

To all whom it may concern:

Be it known that I, MILTON J. ROSEN- GRANTZ, a citizen of the United States of America, residing in the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in Nickel-Chromium Alloys and Processes of Making Same, of which the following is a specification.

This invention relates to metal alloys, and to processes of producing the same, and aims to provide improvements therein.

The invention provides an alloy having as its principal constituents nickel and chromium, which alloyhas various desirable properties and uses. The alloy is non-oxidizable and non-carbonizable at high and ordinary temperatures,is acid and alkali-resistant to a hlgh degree, gives solid, sound, close grained castings, is readily machineable, is malleable and ductile, is readily polished, and possesses a high tensile strength and a low coefilcient of friction. The alloy is hence of primary interest in the chemical, marine and heat-treating industries. The alloy is a good bell-metal and a good antifriction metal.

It has been found that the production of an alloy having the desirable characteristics set out above is largely dependent upon the method provided by the present invention of producing the alloy.

The following glves a full description of the invention, to ether with one particular example of a met 0d, according to the present invention, of producing an alloy embodying the invent1on:-

Before proceeding to produce the final alloy, it is found desirable, if not necessary, to roduce an intermediate alloy or product.

reparation of intermediate product. Nickel from 40% to 80% (for example chromium from 10% to 30% (for example 18%), and silicon, from 5% to 15% (for example 10%) are placed in a crucible, which preferably has been previously warmed, and the batch brought to a molten state, the .temperature of fusion being about 2800 to 2900 F. Molybdenum, about 2%, and zirconium, are now to be added to the melt. The zirconium is preferably added in theform of ferro-zircomum, from 5% to 20% of ferro-zirconium being used (for example 10% Samples of ferro-z1rconium which have been thus used have shown on analysis about 25% zirconlum, the

remaining constituents in the ferro-zirconianied by a rapid .gasification owing to the act that apart of the molybdenum and zir- 7 conium forms oxids or other compounds with impurities in the melt, which oxlds and other compounds being either gaseous or liquid, flow or esca e to the surface of the molten metal and orm slag or go off into the air. In order to effect the introduction of the molybdenum and ferro-zirconium into the melt, I have found it highly desirable to previously heat the molybdenum and ferrozirconium to a degree just under their melting point, and to then immediately and quickly introduce them into the melt, immediately stir, and thereupon to bring the temperature down as rapidly as possible, preferably by immediately casting into ingots. The union of the molybdenum and ferro-zirconium with the melted nickel, chromium and silicon. ould be made to take place almost instantly, as if the molybdenum and ferro-zirconium are maintained at a temperature at or near their melting point for any length of time, they volatilize and pass off, leaving only slag.

In practice it is best to use graphite crucibles in which to make the intermediate alloy, but it is found practically necessary to line these with a refractory non-carbonaceous lining, as, for example, fused alumina, which lining prevents contact between the fused contents and the carbon of which the crucible is made.

It has been found to be of much importance in producing the intermediate alloy, as Well as the final or complete alloy, to exclude carbon as much as possible.

Analysis of the intermediate alloy shows none or but a small proportion of molybdenum and firm-zirconium originally introduced into the melt, the action of the molybdenum and ferro-zirconium being not clearly understood, except as to the results obtained, being probab y a deoxidlzmg or scavenging action. There is, however, produced an effect in the intermediate alloy, which is carried into the final or complete alloy, which effect is important as regards the obtaining in the complete or final alloy of the pro rties thereof hereinbefore mentioned.

e intermediate alloy has a coarse, crystalline structure, and at the present time no particular use therefor is known to me other than its use in connection with the production of the final or complete alloy, and other alloys and metals. steel, the tensile strength, elastic limit and elongation are materially increased by addiililg small percentages of the intermediate a oy.

In forming the intermediate allow, the molybdenum may be omitted, in which case it is advisable to slightly increase the percentage of ferro-zirconium used.

Moreover, in forming the intermediate al- 10y, the silicon may be omitted. The effect of this would be to make the alloy more duetile and less acid-resistant and hence to carry gllilese properties into the final or complete 0 1 ltlibreover, by decreasing the percentage of chromium inthe intermediate alloy, and correspondingly increasing the percentage of nickel therein, the intermediate alloy is less acid-resistant and more ductile, and vice versa where the chromium percentage is increased and the nickel percentage correspondingly decreased. The corresponding properties are carried into the-final or complete alloy.

Preparation of complete or final aZZ0y.-

Nickel from 10% to 45% (for example 35%), chromium from 2% to 6% (for example 3%), and silicon from 1% to 3% (for example 2%), copper from 0 to 2% (for example 1%), and the intermediate alloy referred to above, from 10% to (for example 56%), are placed in a crucible and melted, the melt occurring at about 2900 Aluminum from 0 to 1% (for exam le 1%) and ferro-titanium from 0 to 3% or example 2%) are then added. The alloy is then thoroughly mixed and allowed to remain in this condition at an elevated temperature for several minutes, and is then cooled, preferably by casting into ingots or shapes.

Summary: Nickel, 10-45%; chromium, 26%; silicon, 13%; ferro-titanium, 03%; copper, 0-2%; aluminum, 0-1%; described intermediate alloy, 1060%. a

Graphite crucibles, as in the preceding 7 case, have been employed in practlce, and it g as to exclude the melt or alloy Moreover', in practice it refe is found practically necessa'rytoline these crucibles with a fused alumina coating, so

bon -of the crucible, it being exclude carbon as much 88130351 1e In the manufacture of I from the c n L m t able to first heat the crucibles to a temperature of about 1000 F., then to add 90% of the nickel content, together with the chromium and silicon content, and brin these to a temperature of about 2750 F. e intermediate alloy, together with the remaining 10% of nickel and copper, are melted together in a similar separate crucible and this melted mass poured into the first crucible, and then the heat of the first crucible raised to about 2900 F., as pointed out above. After the mixture has been brought to about 2900 F., the aluminum and ferro: titanium are then added and the melt thoroughly mixed, and poured, as set out above. The addition of the intermediate alloy, especially in a fluid state, has been found to bring about a better union of the metals and to produce a closer metal alloy.

In the manufacture of the com lete allpl :i

the silicon content may be omitte as wo be the case where bell-metal is to be produced,.the alloy being then more ductile and less acid-resistant.

The copper might; also be omitted, but the use of copper has been found desirable as it appears to act as a flux for the nickel and chromium.

The ferro-titanium and aluminum are used as deoxidizers. The aluminum also acts to keep up the tem erature of the mass. Analyses of the comp eted 0r final alloys show no trace, or only a small roportion, of these metals put into the crucible.

A representative sample of the allo. possesses, among others, the following o racteristics:-It is hard, malleable, easily polished and resistant to corrosive action. It is readily machineable, rolled, for ed and .drawn'into wire, and has a low coe cient of friction. The molten metal casts in a closegrained, uniform, dense structure. It has a melting point' of approximately 2460 F.,

and withstands oxidizing and carbonizing of 105,000 to 110,000 Alkalies have no apgrained homogenous The cast alloy has for ex preciable efl'ect u on the metal. The action of vegetable aoi s is unappreciable. It is only slightly affected bythe principal mineral acids when boiling and unappreciably affected by said acids when cold.

The inventive ideas herein disclosed are capable ofbeing ex ressed in practices other than as herein specificallydescribed; Moreover, it will'be apparent that the alloy may be varied within wide asto its constituents, ..whil e mamtainmg ts generic ;vir-

he the-process ma e; in

a separate application filed Serial No. 304,019.

WhatI claim is: 1. A process ofmaking a nickel-chromium alloy comprising meltin nickel and chromium and a previously ormed nickel-chro- June 13, 1919,

- mium alloy which has been treated with zirconium while in a molten state.

2. A process of making a nickel-chromium alloy comprising melting nickel and chromium and treating the melt with Zirconium,

to form an intermediate alloy, and melting further quantities of nickel and chromium, and adding saidintermediate alloy.

3. A process of making a nickel-chromium alloy comprising melting nickel and chromium and treating the melt with zirconium,

toiform an intermediate alloy, and melting further quantities of nickel and chromium,

and adding said intermediate alloy, and excluding carbon from the melt during the process.

4. A process of making a' nickel-chromium alloy comprising melting nickel and chromium and treating the melt with zirconium,

to form an intermediate alloy, and melting further quantities of nickel and chromium, and adding saidintermediate alloy, from 40-80% nickel and from 10-30% chromium being used in producing the intermediate alloy, said intermediate alloy constituting from 10-60% of the final melt, and the additional nickel and chromium being from 10-45% and from 2-6%, respectively.

5. A process of making a nickel-chromium alloy comprising melting nickel, chromium and silicon, and a previously formed nickelchromium alloy which has been treated with zirconium while in a molten state.

6. A process of making a nickel-chromium alloy comprising melting nickel and chromium together with a flux of copper, and a previously formed nickel-chromium alloy which has been treated with zirconium while in a molten-state, the percentage of copper being up to 2%.

7. A process of making a nickel-chromium alloy comprising melting nickel and chromium and treating the melt with zirconium,

and up to 2% respectively.

8. A process of making a nickel-chromium said interme-' alloy comprising melting nickel and chromium and treating the melt with zirconium, to form an intermediate alloy, melting further quantities of nickel and chromium, adding said intermediate alloy, and treating the melt with ferro-titanium.

9. A process of making a nickel-chromium alloy comprising melting'nickel and chromium and treating the melt with zirconium, to form an intermediate alloy, melting further quantities of nickel and chromium, adding said intermediate alloy, and treating the melt with ferro-titanium, from 40-80% nickel and, from 10-30% chromium being used in producing the intermediate alloy, said intermediate alloy constituting from 10-60% of the final melt, the additional nickel and chromium being from 10-45%, and from 2-6%, respectively, and the percentage of ferro-titanium being up to 3%.

10. A process of making a nlckel-chromium alloy comprising melting nickel and chromium and a previously formed nickelchromium alloy treated with zirconium in its molten state, and treating the melt with aluminum.

11. A process of making a nickel-chromium alloy. comprising melting nickel and chromium and treating the melt with zirconium to form an intermediate alloy, melting further quantities of nickel and chromium, together with silicon and copper, adding said intermediate allo and treating the melt with aluminum and erro-titanium, from 40% to 80% nickel, from 10% to 30% chromium and from 5% to 20% zirconium in the form of ferro-zirconium being used in producing the intermediate alloy, said intermediate alloy constituting from 10% to 60% of the final melt, the additional nickel and chromium being from 10% to 45% and from 2% to-6% respectively, the percentage of silicon being from 1% to 3%, the percentage of aluminum being up to 1% and the percentage of ferro-titanium being up 12 An alloy essentially of nickel and I chromiumcontaining from 10% to 60% of an intermediate alloy containing nickel and chromium treated with zirconium while in the molten state, and additional quantities of nickel and chromium, having a dense crystalline structure, said alloy being'acid and alkali resistant, the additlonal quantities of nickel being from 10% to 45% and the additional quantities of chromium being from 2% to 6%.

In witness whereof, I have hereunto signed my name.

MILTON J. ROSENCRANTZ. 

